Friday, March 31, 2017

Torsades de pointes - twisting of the points

DEFINITION
Torsades de pointes is a polymorphic ventricular tachycardia that occurs frequently in cases of QT interval prolongation.

This can be due to congenital or acquired Long QT interval syndrome.

It is characterized by a progressive change of the electrical axis, typically rotating 180 degrees in approximately 10 to 12 cycles and the amplitude, as though the depolarization and repolarization of the ventricle was turning on a point.

This results in the characteristic sinusoidal twisting of the peaks of the QRS complexes around the isoelectric line of the recording.

EKG

The tachycardia rate typically is in the range of 150 to 300 beats/min.

It is usually a self-limiting arrhythmia that spontaneously dies out after a few tens of cycles and only in a minority of cases that it degenerates into ventricular fibrillation and can lead to sudden cardiac death.

Drugs that can prolong the QT interval and induce Torsades de pointes are:

It can also be caused by electrolyte imbalances like, hypokalemia, hypomagnesemia and less commonly hypocalcemia.

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